Bipropellant injector

ABSTRACT

A bipropellant injector consisting of a pair of concave deflector blocks with their concave surfaces facing one another. The concave surfaces diverge downwardly with a fixed spaced relationship between them at the base of the injector. A triangular &#39;&#39;&#39;&#39;shute&#39;&#39;&#39;&#39; is formed in each concave surface, by a pair of diverging sidewalls. The two shutes are opposite one another. A circular orifice is located at the apex of each shute to provide an inlet for propellant, such as fuel or oxidizer to enter the injector. Propellant, forced through each orifice as a circular jet, is directed downwardly along the shute spreading out against the concave shute surface. The propellant spreads to form a sheet which is limited between the shute&#39;&#39;s sidewalls. It finally clears the shute&#39;&#39;s lower edge, and mixes with the propellant flowing from the opposite shute along the centerline of the space between the injector&#39;&#39;s blocks.

United States Patent [451 Mar. 21, 1972 Riebling [54) BIPROPELLANTINJECTOR [72] Inventor: Robert W. Riebling, LaCanada, Calif.

[73] Assignee: James E. Welib, Administrator of the National Aeronauticsand Space Administration 22 Filed: Sept. 25, 1967 21 Appl. No.: 670,829

[52] U.S.Cl ..239/4l8,239/433,239/543 [51] Int. Cl ..F23d ll/l0 [58]Field of Search ..239/4 1 8, 420, 426, 433, 434;

[56] References Cited UNITED STATES PATENTS 1,321,816 11/1919 Foerst....239/426 1,366,685 1/1921 Wilson ..239/434 Primary Examiner-SamuelFeinberg Attorney-G. T. McCoy, .l. H. Ward-en and D. E. Leslie [5 7]ABSTRACT A bipropellant injector consisting of a pair of concavedeflector blocks with their concave surfaces facing one another. Theconcave surfaces diverge downwardly with a fixed spaced relationshipbetween them at the base of the injector. A triangular shute" is formedin each concave surface, by a pair of diverging sidewalls. The twoshutes are opposite one another. A circular orifice is located at theapex of each shute to provide an inlet for propellant, such as fuel oroxidizer to enter the injectsr. Propellant, forced through each orificeas a circular jet, is directed downwardly along the shute spreading outagainst the concave shute surface. The propellant spreads to form asheet which is limited between the shutes sidewalls. lt finally clearsthe shutes lower edge, and mixes with the propellant flowing from theopposite shute along the centerline of the space between the injectorsblocks.

8 Claims, 3 Drawing Figures IMPINGEMENT ANGLE a PAIENTEDMMI I9723,650,474

IMPINGEMENT ANGLE a SPACING Figure 2.

ROBERT w. RlEBLlNG INVENTOR.

A TTORNEYS.

BIPROPELLANT INJECTOR ORIGIN OF INVENTION The invention described hereinwas made in the performance of work under a NASA contract and is subjectto the provisions of Section 305 of the National Aeronautics and SpaceAct of 1958, Public Law 85-568 (72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION l. Field of the Invention This inventionrelates to a propellant mixing device and, more particularly, to animproved bipropellant injector.

2. Description of the Prior Art Since the early development ofbipropellant rocket engines various injecting arrangements have beenconceived. The basic function of a bipropellant injector is to controlthe uniform mixing of the two propellants which are supplied from twoseparate sources, so that satisfactory combustion occurs. To this endimpinging-sheet elements, generally with concave surfaces, have beenused to convert jets of propellants from circular orifices into thinliquid sheets to enhance the uniform mixing of the propellants. Theseelements are sometimes referred to as concave deflectors.

It has been observed that although the use of impingingsheet elements orconcave deflectors in injectors is quite useful, such use results incertain phenomena which are most detrimental to the effectiveness of theinjector, particularly to the uniform mixing of the two propellants. Ithas been observed that when a jet of propellant or liquid from acircular orifice is directed tangentially against a solid concavedeflector surface, the liquid, while spreading into the form of a sheet,develops surface tension wavelets which often produce the followingundesired effects:

1. Upon interaction of the wavelets with the freeboundary of the sheetof liquid on the deflector, they tend to form daughter droplets in muchthe same manner as spray is formed from ocean waves. These droplets arecontinuously cast off from the main sheet of liquid and form largeglobules which then dribble off the deflector in an unpredictablemanner, resulting a nonuniform propellant mixing. Consequently, thisportion of the propellant would be ineffectively combusted and mightcause combustion roughness.

2. The wavelets can persist in the free unbounded sheet of liquidpropellant flowing on the deflector surface and upon the interactionwith the outer peripheral portion or ribs" of the liquid at the edge ofthe sheet could bring about a premature liquid sheet disintegration.

Such undesirable phenomena have characterized the performance of allknown prior art bipropellant injectors, thereby limiting theireffectiveness.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore a primary object ofthe present invention to provide an improved bipropellant injector.

Another object of this invention is to provide a bipropellant injectorin which the number of surface tension wavelets and their undesiredeffect is minimized.

A further object of this invention is the provision of a bipropellantinjector which produces a more uniform mixing of the propellants, thanthat attainable with similar prior art injectors.

Still a further object of this invention is to provide an improvedbipropellant injector in which the flow of propellant is controlled tominimize the number of spray-producing droplets.

These and other object of the invention are achieved by providing abipropellant injector which includes oppositely positioned and spacedapart bounded concave surfaces. Jets of liquid propellants from circularorifices are directed onto these surfaces. Since the concave surfacesare bounded, ac-

tually defining triangular shutes with concave surfaces, the sheets ofliquid which are formed in the shutes are bounded by the shutessidewalls. Consequently fewer spray-producing droplets are created.Furthermore since the sheets of liquids have definite boundaries, thesurface tension wavelets cannot persist along the liquid sheetboundaries to produce undesired premature liquid sheet disintegration.Since the injector of the present invention is used for mixingpropellants in liquid state, the terms propellant and liquid as usedhereafter should be regarded as synonyms.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The inventionwill best be understood from the following description when read inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of the improvedbipropellant injector of the present invention;

FIG. 2 is an isometric view of one of the injectors deflectors and apartial view of the other deflector; and

FIG. 3 is an isometric view of a plurality of injectors mounted on acommon plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2there may be seen an injector 10 which consists of two deflector blocks12 and 14. In FIG. 1 they are shown interconnected at their tops by aheader 15. The header is not shown in FIG. 2 in order to displaysignificant novel features of the injector. The deflector blocks, orsimply deflectors 12 and 14 are positioned so that their respectivesurfaces 16 and 18 face one another in a parallel relationship. Surface16 is machined to define a triangular shute 20 which has a concavesurface 22 and two sidewalls 24 and 25. Similarly, surface 18 ofdeflector l4 defines an identical shute, designated in the figures bynumeral 26. The bases of the the two shutes which are at the base of theinjector 10 are parallel to one another and spaced apart by a distanceD.

A circular orifice 28 is fixedly positioned at the apex of shute 20while a similar circular orifice 30 is fixedly positioned at the apex ofthe shute 26. As is appreciated by those familiar with the art, thefunction of these orifices is to serve as inlets for the two liquidsinto the injector in which they are to be mixed. In FIG. 2 the liquidsare designated FUEL and OX- IDIZER, assumed to be supplied fromappropriate sources (not shown).

In operation the fuel is forced into the injector through orifice 28 andthe oxidizer through orifice 30. The circular jets of fuel and oxidizerissuing from 28 and 30 are directed tangentially downward along theconcave surfaces of shutes 20 and 26. Since the shutes are triangular,the liquids spread out within the shutes against the shutes sidewalls(such as 24 and 25 of shute 20). As a result, the jets of liquid tend toflatten out into even thinner and wider sheets until they clear thelower edges of the shutes. The two sheets of liquid generally impingealong a line 32 at the center of spacing D. Thereat uniformfuel-oxidizer mixture occurs, starting the desired combustion. The angleof impingement a is a function of the curvature of the concave surfacesof the two shutes, at the lower ends which define the injectors outlet.

The circular jet of liquid, issuing from each orifice, does not merelyimpinge a concave surface in order to be converted into a sheet ofliquid. Rather it is issued into a shute which in addition to a concavesurface has two sidewalls or boundaries. Consequently, the formed sheetof liquid is bounded by the sidewalls, which contribute to theelimination or minimization of undesired phenomena which occur in priorart injectors.

Basically, by providing the sidewalls along each shute the sheet ofliquid flowing on the concave surface thereof has a solid boundary,eliminating the formation of a liquid-gas interface which is createdwhen the sheet of liquid is formed on an unbounded surface. Thisminimizes the formation of daughter droplets and the undesired effectsproduced thereby. Furthermore, by directing the sheet of liquid in abounded shute, surface tension wavelets are delfected by the shutessidewalls into the flowing sheet of liquid, thus acting to effectivelycancel the surface tension wavelets.

Reference is now made to FIG. 3 where the bottom sides of a plurality ofinjectors are shown. The injectors are shown supported on a plate 40.Holes 42 are used to accommodate bolts (not shown) by means of which theplate 40 is secured to an engine or the like. Two liquids such as fueland oxidizer are assumed to be supplied to each injector with themixtures produced by the various injectors used to provide the requiredenergy-producing combustion. in FIGS. 1 and 2, the entire surfaces 16and 18 of the deflectors are shown as concave. This may be desirable tosimplify the machining of the bottom surfaces (such as 22) of theshutes. However, for the proper performance of the injector of thepresent invention, it should be appreciated that only the bottomsurfaces of the shutes have to be curved, since the flow of liquid islimited to such surfaces. It should further be pointed out that thedivergence of the sidewalls of each shute has to be such that for anyexpected flow rate of liquid the sheet of liquid formed in the shute isat all times bound by the sidewalls of the shute.

There has accordingly been shown and described herein a novelbipropellant injector which includes shutes, formed by curved bottomsurfaces and boundary-defining sidewalls. The shutes convert jets ofliquid into sheets of liquid, solidly bounded by the shutes sidewalls tominimize the formation of spray-producing droplets and the effects ofsurface tension wavelets. It is appreciated that those familiar with theart may make modifications and/or substitute equivalents in thearrangement as shown without departing from the spirit of the invention.Therefore, all such modifications and/or equivalents are deemed to fallwithin the scope of the invention as claimed in the appended claims.

I claim:

1. An injector for mixing two liquids supplied thereto comprising:

a first shute having a bottom surface uniformly curving from a top endthereof to an opposite bottom end, and a pair of sidewalls on oppositesides of said surface, the walls diverging from one another from saidtop to the bottom ends of said surface, the curved surface between thesidewalls at said top end defining a shute apex and the curved surfacebetween the sidewalls at the bottom end defining a shute base, one ofsaid liquids being injectable at the shute apex;

a second shute having a bottom surface uniformly curving from a top endthereof to an opposite bottom end, and a pair of sidewalls on oppositesides of said surface, the walls diverging from one another from saidtop to the bottom ends of said surface, the curved surface between thesidewalls at said top end defining a shute apex and the curved surfacebetween the sidewalls at the bottom end defining a shute base, the otherof said two liquids being injectable at the shute apex; and

means for fixedly positioning the first and second shutes opposite oneanother with their bases in parallel spaced relationship, the spacetherebetween defining the outlet of said injector with the distancebetween the bases being less than the distance between the apexes ofsaid shutes.

2. The injector as recited in claim 1 wherein said means for injectingcomprise first liquid inlet means fixedly positioned at the apex of saidfirst shute and defining a first orifice through which a jet of liquidis injectable into said first shute, said means for injecting furthercomprising a second liquid inlet means fixedly positioned at the apex ofsaid second shute and defining a second orifice through which a jet ofliquid is injectable into said second shute, whereby the liquidsinjected in said first and second liquid inlet means are combinable onlyin the space defining the injector outlet.

3. An injector for mixing two fluids supplied thereto comprising:

first and second deflecting blocks fixed opposite one another at aspaced apart relationship, each block defining a shute in the surfaceopposite the other block, said shute having a bottom of a continuouspreselected curvature extending from a first end of the block to asecond opposite end, said shute further comprising a pair of sidewallsdiverging from said first end to the second end, the spacing between thebottoms of the shutes at said first ends being greater than the spacingbetween the shutes bottoms at said second ends; and

a pair of fluid injecting means positioned at the apexes of the shutesdefined in said first and second blocks for injecting jets of fluid intosaid shutes at the apexes thereof, whereby the fluid in each shute flowsfrom the shute apex towards the other shute end over said curved bottom,the fluid spreading out to form a sheet of fluid physically bound by thesidewalls of said shutes.

4. An injector for controlling the uniform mixing of two liquidssupplied thereto comprising:

a pair of oppositely positioned liquid-flow-controlling shutes, eachshute having a uniformly curving bottom surface and two sidewallsdiverging from one another from one end of said shute, defining a shuteapex, towards an opposite end, defining a shute base, the bases of saidshutes being parallel and spaced apart from one another to define aninjector outlet, the outlet width defined by the distance between thebases being less than the distance between the shutes apexes; and

two liquid inlet means, each one positioned at the apex of a differentone of said shutes to provide means for injecting one of said twoliquids into the shute, with the liquids exiting the shutes bases beinguniformly mixable substantially along the center of said injectoroutlet.

5. The injector as recited in claim 4 wherein each of said liquid inletmeans defines a circular orifice, whereby the liquid injected into theshute is in the form ofa circular jet ofliquid, spreading out againstthe bottom surface of the shute and forming a liquid-solid boundary withthe shutes sidewalls.

6. The injector as recited in claim 5 wherein the bottom surface of eachshute is concave with the curvatures of the two surfaces at the shutesbases defining an impingement angle at which the liquids, exiting theshutes, are combined.

7. The injector as recited in claim 4 wherein the bottom surface of eachshute is concave with the curvatures of the two surfaces at the shutesbases defining an impingement angle at which the liquids, exiting theshutes, are combined.

8. An injector for controlling the uniform mixing of two liquidssupplied thereto, comprising:

a pair of uniformly curved oppositely positioned shutes, convergingtowards one another from first ends thereof representing shutes apexesat which said liquids are supplied to second ends thereof representingshutes bases, the space between the bases defining an injector outlet,each shute having a uniform concave bottom surface extending from itsapex to its base and a pair of sidewalls diverging from the apex to thebase, whereby two different liquids supplied at the apexes of the shutesspread out therein to form sheets of liquid exiting said shutes bases tobe uniformly mixed at the injector outlet.

1. An injector for mixing two liquids supplied thereto comprising: afirst shute having a bottom surface uniformly curving from a top endthereof to an opposite bottom end, and a pair of sidewalls on oppositesides of said surface, the walls diverging from one another from saidtop to the bottom ends of said surface, the curved surface between thesidewalls at said top end defining a shute apex and the curved surfacebetween the sidewalls at the bottom end defining a shute base, one ofsaid liquids being injectable at the shute apex; a second shute having abottom surface uniformly curving from a top end thereof to an oppositebottom end, and a pair of sidewalls on opposite sides of said surface,the walls diverging from one another from said top to the bottom ends ofsaid surface, the curved surface between the sidewalls at said top enddefining a shute apex and the curved surface between the sidewalls atthe bottom end defining a shute base, the other of said two liquidsbeing injectable at the shute apex; and means for fixedly positioningthe first and second shutes opposite one another with their bases inparallel spaced relationship, the space therebetween defining the outletof said injector with the distance between the bases being less than thedistance between the apexes of said shutes.
 2. The injector as recitedin claim 1 wherein said means for injecting comprise first liquid inletmeans fixedly positioned at the apex of said first shute and defining afirst orifice through which a jet of liquid is injectable into saidfirst shute, said means for injecting further comprising a second liquidinlet means fixedly positioned at the apex of said second shute anddefining a second orifice through which a jet of liquid is injectableinto said second shute, whereby the liquids injected in said first andsecond liquid inlet means are combinable only in the space defining theinjector outlet.
 3. An injector for mixing two fluids supplied theretocomprising: first and second deflecting blocks fixed opposite oneanother at a spaced apart relationship, each block defining a shute inthe surface opposite the other block, said shute having a bottom of acontinuous preselected curvature extending from a first end of the blockto a second opposite end, said shute further comprising a pair ofsidewalls diverging from said first end to the second end, the spacingbetween the bottoms of the shutes at said first ends being greater thanthe spacing between the shutes'' bottoms at said second ends; and a pairof fluid injecting means positioned at the apexes of the shutes definedin said first and second blocks for injecting jets of fluid into saidshutes at the apexes thereof, whereby the fluid in each shute flows fromthe shute apex towards the other shute end over said curved bottom, thefluid spreading out to form a sheet of fluid physically bound by thesidewalls of said shutes.
 4. An injector for controlling the uniformmixing of two liquids supplied thereto comprising: a pair of oppositelypositioned liquid-flow-controlling shutes, each shute having a uniformlycurving bottom surface and two sidewalls diverging from one another fromone end of said shute, defining a shute apex, towards an opposite end,defining a shute base, the bases of said shutes being parallel andspaced apart from one another to define an injector outlet, the outletwidth defined by the distance between the bases being less than thedistance between the shutes'' apexes; and two liquid inlet means, eachone positioned at the apex of a different one of said shutes to providemeans for injecting one of said two liquids into the shute, with theliquids exiting the shutes'' bases being uniformly mixable substantiallyalong the center of said injector outlet.
 5. The injector as recited inclaim 4 wherein each of said liquid inlet means defines a circularorifice, whereby the liquid injected into the shute is in the form of acircular jet of liquid, spreading out against the bottom surface of theshute and forming a liquid-solid boundary with the shute''s sidewalls.6. The injector as recited in claim 5 wherein the bottom surface of eachshute is concave with the curvatures of the two surfaces at the shute''sbases defining an impingement angle at which the liquids, exiting theshutes, are combined.
 7. The injector as recited in claim 4 wherein thebottom surface of each shute is concave with the curvatures of the twosurfaces at the shute''s bases defining an impingement angle at whichthe liquids, exiting the shutes, are combined.
 8. An injector forcontrolling the uniform mixing of two liquids supplied thereto,comprisIng: a pair of uniformly curved oppositely positioned shutes,converging towards one another from first ends thereof representingshutes'' apexes at which said liquids are supplied to second endsthereof representing shutes'' bases, the space between the basesdefining an injector outlet, each shute having a uniform concave bottomsurface extending from its apex to its base and a pair of sidewallsdiverging from the apex to the base, whereby two different liquidssupplied at the apexes of the shutes spread out therein to form sheetsof liquid exiting said shutes'' bases to be uniformly mixed at theinjector outlet.